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32 .\" @(#)mpool.3 8.1 (Berkeley) 6/4/93
40 .Nd "shared memory buffer pool"
45 .Fn mpool_open "void *key" "int fd" "pgno_t pagesize" "pgno_t maxcache"
49 .Fa "void (*pgin)(void *, pgno_t, void *)"
50 .Fa "void (*pgout)(void *, pgno_t, void *)"
54 .Fn mpool_new "MPOOL *mp" "pgno_t *pgnoaddr"
56 .Fn mpool_get "MPOOL *mp" "pgno_t pgno" "u_int flags"
58 .Fn mpool_put "MPOOL *mp" "void *pgaddr" "u_int flags"
60 .Fn mpool_sync "MPOOL *mp"
62 .Fn mpool_close "MPOOL *mp"
66 library interface is intended to provide page oriented buffer management
71 function initializes a memory pool.
74 argument is currently ignored.
77 argument is a file descriptor for the underlying file, which must be seekable.
81 argument is the size, in bytes, of the pages into which the file is broken up.
84 argument is the maximum number of pages from the underlying file to cache
86 This value is not relative to the number of processes which share a file's
87 buffers, but will be the largest value specified by any of the processes
92 function is intended to make transparent input and output processing of the
96 function is specified, it is called each time a buffer is read into the memory
97 pool from the backing file.
100 function is specified, it is called each time a buffer is written into the
102 Both functions are called with the
104 pointer, the page number and a pointer to the page to being read or written.
110 pointer and an address as arguments.
111 If a new page can be allocated, a pointer to the page is returned and
112 the page number is stored into the
125 pointer and a page number as arguments.
126 If the page exists, a pointer to the page is returned.
134 argument is not currently used.
138 function unpins the page referenced by
143 must be an address previously returned by
149 argument is specified by
151 any of the following values:
152 .Bl -tag -width indent
154 The page has been modified and needs to be written to the backing file.
160 returns 0 on success and -1 if an error occurs.
164 function writes all modified pages associated with the
171 returns 0 on success and -1 if an error occurs.
175 function free's up any allocated memory associated with the memory pool
179 written to the backing file.
183 returns 0 on success and -1 if an error occurs.
187 function may fail and set
189 for any of the errors specified for the library routine
194 function may fail and set
199 The requested record does not exist.
206 functions may fail and set
208 for any of the errors specified for the library routines
216 function may fail and set
218 for any of the errors specified for the library routine
223 function may fail and set
225 for any of the errors specified for the library routine